class_docstr: This class is responsible for building components for semantic segmentation. 
code: def val_dataset(self) -> paddle.io.Dataset:
      dataset_cfg = self.config.val_dataset_cfg
      assert (
          dataset_cfg != {}
      ), "No val_dataset specified in the configuration file."
      self.show_msg("val_dataset", dataset_cfg)
      dataset = self.build_component(dataset_cfg)
      if len(dataset) == 0:
          logger.warning(
              "The number of samples in val_dataset is 0. Please ensure this is the desired behavior."
          )
      return dataset
  
imports: import copy
  from typing import Any, Optional
  import yaml
  import paddle
  from paddleseg.cvlibs import manager, Config
  from paddleseg.utils import utils, logger
  from paddleseg.utils.utils import CachedProperty
label_desc: Use image node_id 9 for calling the SegBuilder obj's underlying member method code with example usage: obj.val_dataset() and returns: dataset